My two cents on the PD: I've been trying out the PD lately, I've thought a lot about it, and here are some notes. For reference, I have a yellow 172 P-PD and a red 170 S-PD. I'm throwing them RHBH and maxing out at about 410' with flat shots. RHFH they quit about 300'.
1. It loves to turn nose down at the end of the flight. This is easy to do with a disc like the leopard or a beat roc: you flip it up to flat from a steep hyzer angle, it turns nose down and fades straight forward. What's amazing to me is that the PD (particular in P plastic) does this when flipped from only a slight hyzer angle. I think this is the main reason the PD can be so straight. The benefits of this are obvious.
2. The PD is not really true stable the way the TB is. It's a little understable. (Out of the box, both PDs had less HSS than my 2 year old beat 170 Star TB.) If you throw the PD hard enough to get some turn out of it, it's a magically slow and consistent turn that persists until very late in the flight. Despite this, in head wind, it doesn't become flukey. It turns more, yes, but is plenty consistent. I'm quite confident throwing flip up hyzer shots into head wind with the PD in either plastic.
3. With a little more hyzer and spin, the behavior described in (2) is easily avoidable: the disc flips little and bites hard left with a lot of glide for hyzer shots with a plenty of horizontal movement. Of course, most discs behave this way, but the point is, it's a lot more versatile than a disc like the leopard.
4. The PD will hold an anhyzer forever. I can't wait to get the P really beat because I think it'll become a really long consistent turnover disc.
5. The PD is less nose angle sensitive than most discs in it's speed class.
6. In view of 1-5, the P-PD consistently reminds me of the worlds longest mid-range. I often throw shots with it that look like the huge flip up roc shots I've seen from players with much more power than me. That's pretty cool!
7. I rarely throw the Surge much farther and the PD has a much smaller rim. With it's straight fade, it's very long, and sufficient for all but the longest low hyzer/fade shots (a la Boss). It's distance/rim width ratio is awesome. I rarely throw max distance discs anymore.
8. I have much more success throwing forehands with the PD than the Teebird. I'm not sure why. I've put a lot of effort into throwing the TB forehand and can do it ok. But the PD immediately produced the most effortless clean releases. Maybe it's the shape of the rim, maybe it's because I suck. I have no idea. Regardless, I'm getting noticeably more birdies from forehand drives now than ever before.
9. In view of 1-8, the PD has to be one of the most versatile golf discs ever created. I can imagine why someone with more power than me might want to stick with the teebird for stability (occasionally the PD holds right a little longer than I expect), but for me it's ideal. It easily covers everything but the most overstable and most understable shots (backhand and forehand) in all sorts of wind.
I'm seriously thinking of rebuilding my driving game around it.
p.s. I'd love to hear what other people have to say about some of these points (especially 1).
